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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        // 简单数据类型 BigInt()
        // 构造函数  代码可读性
        const wes = Symbol('Wes');
        const person = Symbol('Wes');
        console.log(wes == person);// false 独一无二
        const classRoom = {
            [Symbol('Mark')]:{grade:50,gender:'male'},
            [Symbol('Oliva')] : {grade:80,gender:'female'},
            [Symbol('Oliva')]:{grade:85,gender:'female'},
            "dl":["cc","11"]
        }
        // console.log(classRoom);
        // for key in 
        // Symbol key 不可以被枚举
        for(const person in classRoom){
            console.log(person,'///');
        }
        const syms = Object.getOwnPropertySymbols(classRoom);
        // console.log(syms);
        const data = syms.map(sym => classRoom[sym]);
        console.log(data);
    </script>
</body>
</html>